Here’s the rosy scenario of a future where cars drive themselves: Instead of owning cars, people will summon autonomous vehicles, hop in, and head to their destination. With fewer cars to be stored, parking lots and garages will give way to development, eventually bringing down the cost of housing in tight markets through increased supply. Pressure to expand roads will ease, as vehicle-to-vehicle technology allows more cars to use the same road space. Traffic violence will become a thing of the past as vehicles communicate instantly with each other and the world around them.

Then there’s the other scenario: People who can afford it will pay an exorbitant amount for gee-whiz driverless technology, but the new systems will have imperfections and won’t integrate seamlessly with older vehicles. Most cars will still be piloted by humans, so the new tech won’t have much effect on traffic hazards and congestion. The driverless car utopia will remain a Magic Highway fantasy.

Driverless vehicle technology has progressed far enough that we need to start anticipating its potential effects. Google’s autonomous vehicle fleet has driven half a million miles without a crash. But the future is extremely uncertain.

The best possible scenario involves a fleet of shared driverless cars and the elimination of private vehicle ownership. Cars would be in constant use, so the amount of land reserved for parking could be greatly reduced. Even if driverless car technology comes on the market soon, however, that version of the future may never arrive.

Here’s how RAND and others are gaming out some of the potential effects:

Parking. Even without shared ownership, autonomous vehicles could go park themselves and lessen the pressure to build parking next to every destination and residence, freeing up large amounts of city land. With less space set aside for car parking, more could be devoted to residential development, for example, making housing more affordable.

Fuel and Emissions. The land devoted to fueling stations could decrease too, since cars could drive themselves to farther-out stations. Autonomous cars would also use less energy than conventional vehicles since they would accelerate and brake much more efficiently than humans. And if they don’t need to be built to withstand crashes — still an enormous “if” — driverless cars could be made of lighter materials, which would be more efficient.

Congestion. This is a tough one. If cars are often driving around empty to find distant parking lots or fuel stations, or to or from a pickup, that’s a lot of extra driving. Still, autonomous vehicles, with sensors that are more perceptive than human beings, could drive much closer together, packing more cars on the same amount of road space without slowing down traffic.

On the other hand, the cost of congestion could be reduced so greatly that people wouldn’t think twice before taking long car trips, and that could increase the number of cars on the road. After all, if you can sleep or work or have a martini on your commute, you might not mind a long one.

Safety. This is considered to be the most clear-cut benefit of self-driving cars. “Every driver believes that he or she is above average,” Anderson said. But human error is behind the great majority of crashes.

“We can see the promise of this kind of technology exercised on a daily basis with crash avoidance systems, cruise control, sensors that aid the driver, backup technology,” former U.S. Transportation Secretary Rodney Slater told Streetsblog. “You see it play out in small snippets. Now, we have the possibility of combining all that with autonomous driving.”

Still, there are questions. The sensors on autonomous vehicles don’t allow for the same give and take that occurs when a pedestrian makes eye contact with a driver. Would driverless cars be programmed to always stop for people walking and biking, or would the assumption be that those people have to stop for the cars? And the sensors won’t necessarily perceive every potential conflict, like when someone is on the sidewalk, about to step off.

Transit. The conventional wisdom seems to be that driverless cars would make transit obsolete by offering convenient, point-to-point personal transport to everyone. Now you’re beginning to see why the effects on congestion and emissions are a big question mark.

But assuming that most people in this brave new world will still work 9 to 5 outside the house, transit will always be the most efficient way to move a lot of people at one time. And driverless technology could be enormously helpful for transit, too.

“The largest cost for transit agencies typically is labor,” said Jeff Wood of the Overhead Wire on the Talking Headways podcast he and I co-host. “I don’t want to say taking away jobs from people is a good idea, but the bus is an untapped resource — especially in areas where it might not be cost-effective right now to run a bus that has seven people on it. In a driverless bus scenario, you have an opportunity to serve more people with greater frequency.”

Subsidies. One obstacle to large-scale adoption of driverless cars is that there’s “a disconnect between who gets the benefits and who might bear the costs,” said Anderson. That’s nothing new: These days, drivers are free to rack up the miles without absorbing negative externalities of their driving — everything from oil wars to asthma. That could flip with the “positive externalities” of self-driving cars, says Anderson, which could accrue more to society than to the driver herself. Enhanced safety, congestion reduction, lower energy consumption, and land use benefits are shared at the societal level. Would purchasers pay for that? Or do the societal benefits call for a public subsidy to accelerate adoption?

The transition. In the early years, there will likely be even fewer benefits for the driver. There will almost certainly be a significant period during which cars can more or less drive themselves, but human drivers will need to be ready to take over at a moment’s notice in difficult situations. “You might pay for that if you have a particularly hellacious commute,” Anderson said, “but at what price point?”

Even the remote possibility that human intervention could be needed obliterates the lion’s share of the benefits of autonomous vehicles. Blind people and children still wouldn’t be able to use the cars. You still couldn’t sleep in a moving car. The car wouldn’t be able to drive itself to gas up or park or pick you up. There will likely be many years when driverless cars remain an expensive gizmo that doesn’t actually dramatically change the transportation landscape.

Anderson suggested that a sort of halfway version of the technology could be rolled out today — like a low-speed driverless jitney to go around college campuses, for example.

Liability. If a driverless car crashes, who’s responsible? The conventional wisdom is that the manufacturer is — and that’s a motherlode of liability automakers don’t want to take on. “Imagine a technology that has the potential to save many, many lives, but it only works, say, 98 percent of the time,” Anderson said. “From a societal perspective, we may want that technology. However, if you’re an automaker and you know you’re going to be sued one out of every 50 times, you might have some very serious reservations about introducing that kind of technology.”

RAND has brainstormed other options, including a version of strict liability for the vehicle owner, whether or not he’s technically at fault. But what if no one’s even in the car at the time of the crash? What happens in a shared-fleet future where cars aren’t even privately owned?

However, air bags were invented in the fifties but not even introduced until the seventies, and they weren’t standard in cars until the nineties, Anderson said. The technology has existed for decades to equip each car with automatic tire pressure monitoring, but in 2014 only a tiny fraction of the vehicle fleet is equipped with that.

The technology for self-driving vehicles may exist, but how long will cost, liability, and other concerns keep it off the market, or at least out of widespread use? Looking at it through that lens, 2020 seems to be a pretty optimistic projection.

This fantasy is not going to come to pass until we experience a radical improvement in the capabilities of AI and software in general. Yes, the cars can drive themselves on the freeway. But they are completely hopeless in any kind of novel scenario. Any random drunk hobo could just sit in front of a self-driving car, laughing his ass off for hours. Or you could put a flowerpot in the crosswalk and the car will sit there forever.

Even if the cars can park themselves 99.9% of the time, it will be a total disaster. Humans park their cars successfully something like 99.99999% of the time.

This new technology can recognize objects. If a person gets in your way and stays in front of your vehicle that is obstruction. The vehicle may be able to take another route and or you would call 911 in that event I would assume,

Recognizing humans or larger animals is somehow a piece-of-cake from AI perspective. We have that deployed right now. Google cars have tested it extensively, as the article mentions.

For about 150 years we’ve had railways. It is fairly easy for a determined person to cause some havoc (or sometimes a major accident) by meddling with rail tracks. It doesn’t take too much to disable a switch, forcing all trains to stop, for instance.

Yet, rarely anyone is dead-set on disrupting rail traffic.

The solution is to prosecute those who interfere with vehicular operation like that (putting debris on a crosswalk on purpose with malice) with criminal statuses like the ones that exist for cutting communication cables, for instance.

I might be interested in this when we have technology with the ability to recognize a light rain.

The big challenge with this technology won’t be so much how it recognizes obstacles, or even how it maneuvers on a freeway full of traffic driven by humans. You can expect humans to behave in certain ways and have the car programmed to react accordingly. You can preset it to defer to human aggression, for instance. But let’s say you have a freeway full of these things, all of them programmed to defer to the others. You have a freeway full of robot cars, and a car in far left lane wants over to exit. Humans work that sort of thing out instinctively, but you can’t program that instinct. How do the robot cars decide who defers to whom? What happens is that everybody defers, and you have a cascading effect of programmed cars slowing down for each other. We are not yet anywhere near the point where a freeway full of independent robot cars can function together. I doubt we’ll get there for at least a couple of decades, and probably not for much longer.

I don’t understand why the goal of having a bunch of empty robot cars roaming around on their way to pick people up is a good thing. We already have plenty of congestion from cars carrying one person. How will adding a bunch of cars carrying no people help?

I don’t think the deferring issue is a big problem. In the computer world it is known as “arbitration” and it occurs a bazillion times a second on the internet. Granted, the real world road situations are more complex and more analog but the same analysis techniques and solutions apply.

That’s not to say that I don’t think that there are other more important issues with self-drive.

I suggest that if you have your car set to “aggressive”, and I have mine set to “causal”, and your car wants mine to get out of its way, the cars simply exchange messages to that effect. Then my car sends a message saying it takes PayPal and the bidding begins. Using pre-set totals, the cars quickly come to a price for mine to move out of the way. It does that, let’s your car by, and I am, say 48 cents richer as a result.

Driverless vehicles could start as very local “shuttles” to get people and goods back and forth from places like Costco. They could be limited to 35 mph. They can also drop people off at transit stations meaning, that we can build fewer of them, further apart and mostly fast rail.

Driverless cars could help eliminate human error in some cases, but I don’t think it can do it as a stand alone project. Maybe adding other systems such as our BiModal Glideway, could assist in making the roads safer for all traffic not just personal but public and commercial as well. Watch our video at bimodalglideway.com

I don’t get the benefit in metro areas with a taxi system already in place. The potential of technology error simply replaces human error. And we have thousands of people who have lost their means of income.

For liability:
1) If it’s clearly a fault like Toyota’s sticking breaks, that’s manufacturer straight up
2) Virtually any other accident should be covered by a general fund – perhaps covered by a minor tax on electricity or usage.

Your suggestions involve more VMT driving to remote parking and remote fueling stations. You don’t consider that more VMT means more fuel consumption and more greenhouse gas emissions (unless we go to cars powered by clean electricity at the same time).

You omit one of the biggest benefits. Cars could be programmed to obey the speed limit, which would make it possible to lower the speed limit. Currently, drivers disobey low speed limits unless there are traffic-calming devices, which cost money to install. With driverless cars, cities could just change the legal speed limit to, say 15 or 20mph on large numbers of residential streets. If even half of cars are driverless, they will also slow down the cars behind them. (In fact, even without driverless cars, we could require cars to have GPS based safety devices that find the speed limit on the current street and prevent the driver from disobeying the law.)

An interesting unintended consequence is that driverless cars will stop for pedestrians who are crossing illegally – unlike drivers, who may hit them or at least curse them out. I think pedestrians will learn when they can safely walk out right in front of slowly driving cars. On busy streets, pedestrians could stop traffic completely by constantly crossing mid-block.

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